Lock mechanism

ABSTRACT

A lock mechanism including a lock member which is normally held in an engaged position to be magnetically operated from said engaged position to a disengaged position, said lock member comprising a spring blade and an engagement member projecting therefrom transversely to the flat side of the spring blade at one end thereof, the spring blade being fixedly secured at the other end thereof, and a safety device for CD boxes having such a lock mechanism.

BACKGROUND OF THE INVENTION

The present invention relates to a lock mechanism comprising a lockmember which is normally held in an engaged position to be magneticallyoperated from said engaged position to a disengaged position.

The lock mechanism of the invention has been developed particularly fora safety device for boxes for compact discs, which is used in the retailtrade for blocking the box so that it cannot be opened easily for theftof the compact disc, or such theft in any case cannot take place withoutconsiderable difficulties. In one safety device which has appeared onthe market in order to protect boxes for compact discs the lockmechanism is of the type referred to and comprises a metal pin guidedfor reciprocating movement and biassed to the engaged position by ahelical spring said pin being provided with a metal head which isattracted by a magnet when it is desired to disengage the lockmechanism. In the engaged position the pin engages an aperture providedin one of the narrow sides of the box. This prior art lock mechanism issafe and reliable, but it is rather expensive in manufacture.

In the compact disc retail trade there is a desire of minimizing thecosts and efforts for protecting the compact discs against theft, andaccordingly there is a demand for cheap protecting devices, which areeasy to handle in the retail store and provide an acceptable protectionof the compact discs, which means that there is a demand for a cheap andeffective lock mechanism for use with such protecting devices.

SUMMARY OF THE INVENTION

The invention provides a lock mechanism of the type referred to abovewhich combines safety with simplicity and low manufacturing costs,wherein the lock member comprises a spring blade an engagement memberprojecting therefrom transversely to the flat side of the spring bladeat one end thereof, the spring blade being fixedly secured at the otherend thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to explain the invention in more detail an embodiment thereofwill be described below reference being made to the accompanyingdrawings in which

FIG. 1 is a side view, partly a vertical cross-sectional view, of asafety device with the lock mechanism of the invention

FIG. 2 is a fragmentary vertical cross-sectional view of the lockmechanism when it is in the engaged position,

FIG. 3 is a view corresponding to FIG. 2 showing the lock mechanism inthe disengaged position, and

FIG. 4 is a perspective view of the spring with the engagement memberforming an integral part thereof.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The safety device disclosed in the drawings is intended for a box for acompact disc (CD). It is injection molded of plastics material, forexample polycarbonate, which is a strong and for the purpose well suitedplastics material. Preferably, the plastics material is crystal-clear.The device is formed as a flat rectangular frame having three walls 10,11 and 12 which form narrow sides of the frame, a wall 13 at one flatside of the frame, forming an opening 14, and two triangular cornerportions 15 and 16 and a rail 17 at the other flat side of the frame,said triangular corner portions connecting the walls 10, 11 and 11, 12,respectively, the rail 17 being located at the narrow side having nowall. At the open narrow side of the frame the wall 13 is retracted inthe longitudinal direction of the walls 10 and 11 in relation to therail 17 for productional reasons, and for the same reasons aperturescongruent with the corner portions, are provided in the wall 13. Theframe is provided with one or more sensors (not shown) for affecting anelectric alarm system when the safety device is carried through the exitof a retail store.

The CD-box is inserted into the safety device by being pushed leftwardsas seen in FIG. 1 into the frame through the open narrow side to theright in FIG. 1. When the box is located in the frame it is encircled bythe frame along three edges and at the two flat sides by the wall 13 atone flat side and by the corner portions 15 and 16 and the rail at theother flat side.

A lock mechanism for interlocking the frame and the CD box inserted intothe frame comprises a spring blade 19 which forms a slightly angled endportion 19' which is supported on a pillar 20 projecting from the wall10 of the frame and having a sloping upper surface the slope of which isadapted to the shape of the housing 18. The end portion 19' forms anaperture 21, and the spring is clamped between said sloping surface ofthe pillar 20 and the inside surface of the housing 18, a smallprotuberance 22 on the sloping surface of the pillar penetrating throughthe aperture 21 into a recess in the inside surface of the housing. Thespring blade at the other end thereof has a flap 23 forming an integralpart of the spring blade 19 and extending downwards transversely of theflat side of the spring blade substantially perpendicularly to saidsurface. As will be seen from the drawings the flap 23 has L-shape asseen in side view one limb of the L connecting to the spring blade andthe other limb projecting downwards. Furthermore, the flap is slightlycurved between the end connecting to the spring blade and the free endof the flap so that the free end is located in a plane transverse to theflat surface of the spring blade, substantially midway between the sideedges of the spring blade, as will be seen in FIG. 4. The flap 23 formsthe engagement member of the lock mechanism, and as will be seen itextends through an aperture 24 in the wall 10 of the frame. Normally thespring blade takes the position shown in FIGS. 1 and 2, the flap 23projecting from the lower side of the wall 10.

A box for a compact disc usually on one half thereof has two laps forthe retention of a printed insert of paper or plastics having adecoration and/or information on the disc in the cassette, and forproductional reasons the narrow side of the cassette at each lap formsan aperture. An aperture of this type is utilized in the safety deviceof the invention for positive engagement between the frame and theengagement member by said member engaging the aperture when in theposition according to FIGS. 1 and 2. The frame thus is locked to the boxand prevents the box from being opened for removal of the disctherefrom.

When the box is being slid into the frame from the right as seen inFIGS. 1 and 2 the flap 23 will be pushed away by the box against thebias of the spring blade and then, when in register with the aperture inthe CD box, will lockingly snap into said aperture under the bias of thespring blade. The frame is thus locked to the box and prevents the boxfrom being opened for removal of the disc therefrom. The spring bladeshould be so stiff that in the engaged position the flap 23 cannot becammed from the aperture in the CD box under bending of the spring bladeif one is trying to slide the box manually out of the frame to the rightas seen in FIGS. 1 and 2 with the lock mechanism in the engagedposition. Every effort to do this will result in the spring blade beingbent downwards against an abutment 25 projecting from the wall 10 of theframe, and the flap 23 being pressed against the right hand boundingsurface of the aperture 24.

Displacement of the flap 23 to the disengaged position in FIG. 3 iseffected by attracting the spring blade by a magnet which is advancedfrom above towards the lock housing from the outside thereof. Due to thestiffness of the spring blade a very strong electric magnet or apermanent magnet of high-quality magnet material is required in order tobring the spring blade to the position according to FIG. 3; it shouldnot be possible to use any simple permanent magnet for the purpose. Inthe position according to FIG. 3 the flap 23 is withdrawn from theaperture in the cassette. Then, the cassette is free to be withdrawnfrom the safety device. This operation should of course be performed byan authorized person only, viz. the shop attendant when the productprotected by the safety device is being sold.

Though developed particularly for use with a CD box protecting safetydevice the lock mechanism of the invention can be used also in devicesof other kinds in order to lock two independent elements againstrelative displacement the lock mechanism being mounted to one of saidelements to engage the other one of said elements at the engagementmember formed by the flap 23.

The illustrative embodiment described can be modified particularly withregard to the construction of the engagement member. Although shown hereas an integral part of the spring blade the engagement element can bemade as a separate element which is attached to the spring blade. E.g.the engagement member could be made as a pin attached to the springblade and projecting from the lower side of the spring blade. However,the flap forming the engagement member in the embodiment described hasbeen found to provide maximum safety against unauthorized removal of theCD box from the protecting frame of the safety device.

I claim:
 1. Safety device for a box including two hingedlyinterconnected rectangular box halves, comprising:a frame to be mountedon an outside of the box encircling the box to prevent opening thereof;a flat spring blade of a material allowing the spring blade to bemagnetically attracted; means for fixedly mounting said spring blade tosaid frame at one end thereof, said spring blade projecting toward theother free end of the spring blade from said mounting means; a flapbeing bent from said spring blade to project therefrom transversely of aplane of the spring blade at said other free end thereof towards aninterior of said frame to lockingly engage a box encircled by the frameand thus to prevent removal of the frame from the box; and a housingenclosing said spring blade exteriorly of the frame, said flap beingdisengaged from the box by magnetically attracting said spring bladefrom the outside of said housing.
 2. Safety device as in claim 1 whereinthe flap is L-shaped as seen in side view thereof, one limb connectingto the spring blade the other one projecting therefrom.
 3. Safety deviceas in claim 1 wherein the flap is curved so as to have the other freeend thereof located in a plane transverse to a flat side of the springblade, substantially midway between side edges of the spring blade.